In prior art is known many different types of vacuum cleaner nozzles for floor cleaning. One object with a vacuum cleaner nozzle is to pick up as much as possible of different kinds of debris and dust from all different kinds of surfaces, such as hard floors or carpets, with as little effort as possible.
A common feature for all kinds of vacuum cleaner nozzles, is that some kind of means has to be provided in order to achieve an optimal combination of vacuum and airflow with high speed around the particles to allow withdrawal by the airflow into the suction opening. This is normally achieved by arranging a bottom plate of the nozzle close to a surface to be cleaned, often also in combination with surrounding the bottom plate area with a low edge, often provided with bristles, which restricts the air flow to the suction opening and forces the air flow as close to the floor as possible. The edge of bristles is normally retracted when cleaning carpets such that the bottom plate is sliding directly onto the carpet in order to draw the air flow between the carpet fibers. However, a vacuum cleaner nozzle arranged in this way involves some disadvantages. For example, a low front edge, such as an edge of bristles results in that larger particles often are pushed in front of the nozzle when moving it over a surface to be cleaned. A low bottom plate distance to the floor increases pick-up from depth, crevices, in between tiles, etc, but also increases the risk for scratching the floor. A strong vacuum underneath the nozzle increases air speed but also the resistance when moving the nozzle. High air speed results in good debris pick-up but also creates more noise.
Many vacuum cleaner nozzles comprises a setting mechanism for setting between the different modes when vacuum cleaning of carpets and hard floors, such that when vacuum cleaning of carpets, the bottom plate is closer to and often slides on the carpet surface in order to draw the air flow between the carpet fibers, whereas when vacuum cleaning of hard floors, the bottom plate is elevated on a distance from the floor surface and the vacuum cleaner nozzle is moved over the surface by sliding on felt or bristle members or rolling on wheels. Such a setting mechanism will of course increase the costs for the vacuum cleaner nozzle and it involves an additional inconvenience for the user to perform the setting.
Some vacuum cleaner nozzles are of an active kind having a rotary driven brush in contact with the surface to be cleaned, in order to achieve a higher degree of pick-up of debris and dust, especially on carpets. However, also when using a rotatable brush, the nozzle has to be provided with a low edge, e.g. of bristles or hard plastics, in order to restrict the air flow towards the suction opening, since a rotatable brush is highly air permeable. This has to effect that also here the pick up of larger items is prevented unless the nozzle is lifted from the surface. Also, when using a rotatable brush on hard floors, it is a risk that the brush will damage the floor during long time use, since bristles in rotatable brushes often are made of a comparatively hard material in order to achieve a sufficient stiffness. Moreover, dust and long flexible items, such as threads and hair, tend to adhere easily to brushes and be difficult to remove. Normally, an actively rotary driven brush is driven at about 3000 rpm (revolutions per minute), which will lead to a tendency for particles to be swept aside instead of being picked up by the nozzle.
In EP 313403 and 338780 is disclosed vacuum cleaner nozzles having a rotatable shaft provided with flexible blades arranged helically around the circumference of the shaft. The rotatable shaft is positioned at the bottom side of the nozzle in front of an air intake opening and an object is to provide an agitator roller, which do not present the usual problem, associated with rotatable brushes, that elongated items, such as threads and hair, tend to get entangled with the bristles of the brush. In all other respects the agitator rollers disclosed in these documents present the same disadvantages associated with rotatable brushes. For example, an agitator roller formed in this way is highly air permeable, such that the nozzle has to be provided with a low front edge, in order to restrict the air flow towards the suction opening, wherein the low front edge will prevent pick up of large items.
Also in WO 9943250 is disclosed a vacuum cleaner nozzle having a rotatable shaft provided with elongated, flexible blades or strip-shaped elements, such as brush strips or blades of rubber or plastics, around the periphery of the shaft. The nozzle is arranged such that, when cleaning hard floors, the outer edges of the blades will not be in contact with the floor but will rotate on a distance above the floor. This is a disadvantage since thereby is not achieved any polishing effect of the floor surface, which would be the case if the blades were in contact with the floor. Moreover, a roller of this kind being provided with flexible blades, is not adapted to wholly or partially support the nozzle against the floor. Instead, the nozzle has to be provided with separate wheels, sliding surfaces or the like. This has to effect that the roller can not follow any irregularities in the floor so well, such that if the floor has any cavities or the like, the roller might pass on a rather large distance from the bottom of the cavity. This will result in a lowered air velocity and deteriorated ability to pick up debris. Also the ability for the nozzle to climb up on edges, such as carpet edges, will be poor if the roller can not support the nozzle. A rotating roller having blades, wings or fins will also generate quite a lot of noise, which is a great disadvantage when vacuum cleaning at the same time as other activities is going on in the same or adjoining rooms.
In US 2005/0071948 is disclosed an attachment for a vacuum cleaner nozzle. The attachment is provided with two rollers and is adapted to be combined with nozzles having a rotatable driven brush. More precisely, a nozzle is to be positioned on top of the attachment, such that the driven brush is in contact with the rollers and the rotary motion of the brush will be transferred to the rollers. The purpose is that the nozzle alone should be used on carpets, since the rotatable driven brush is well suited to pick up debris and dust from between the carpet fibers, whereas the nozzle together with the attachment should be used on hard floors. Besides that the combination of the nozzle and the attachment will be very cumbersome to use, since it will have a considerable height which will make it impossible to vacuum clean under furniture and the like, the rollers will be driven in the same direction, having to effect that one of the rollers will sweep the debris and dust towards the suction opening, whereas the other roller will sweep the debris and dust away from the suction opening. Also, the rollers are mounted in the attachment with rather large gaps between the portions of the rollers which are facing outwards and the attachment, such that an essential part of the air flow will go this way. Accordingly, the cleaning effect will be poor.
In the Japanese published patent application 2007-105244 is disclosed a cleaning roller consisting of an inner core on the outer periphery of which is provided a foamed body. The foamed body is preferably of polyurethane foam and has a thickness of at least 5 mm. The outer periphery of the foamed body is cylindrical with a circular cross section and the surface is provided with 10 to 40 open pores per 25 mm. The object of the cleaning roller is that debris and dust shall adhere to the open pores of the roller surface when moving the roller over the surface to be cleaned. The cleaning roller is illustrated as being mounted onto a handheld cleaning tool, such that the roller can be moved over the surface to be cleaned by hand. However, it is mentioned in the specification that the cleaning roller also could be arranged at a dust suction opening of a vacuum cleaner.